An electronic control unit (ECU) controls fuel injection for an internal-combustion engine and ignition in each cylinder of the internal-combustion engine based on parameters such as the amount of intake air. The ECU obtains the amount of intake air based on an electric signal outputted through a harness from a flow measuring device. The ECU computes the fuel injection timing and period, ignition timing, etc. using the amount of intake air to perform the fuel injection and ignition.
An electric signal (such as flow signal) outputted from a flow measuring device has a rectangle wave shape with a rising edge and a falling edge in a signal value. The flow measuring device applies a control voltage to a switching element disposed in an output wiring, and a voltage of a logic high or a logic low is output to the output wiring, for the ECU.
For this reason, the flow signal contains harmonic component, which may become a source of noise, such that an apparatus around a harness corresponding to the output wiring may be affected. JP 2865785 B2 describes a delay circuit in which a switching element and a capacity element are connected in parallel so as to make a rising and a falling in the waveform gentle. However, each of the rising and the falling itself is still steep, such that a flow signal may still become a noise source in JP 2865785 B2.